mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-14 17:44:06 -08:00
848cb5a6d6
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
389 lines
11 KiB
Go
389 lines
11 KiB
Go
// Copyright 2021 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tsdb
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import (
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"fmt"
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"math"
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"runtime"
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"sync"
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"time"
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"github.com/go-kit/log/level"
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"github.com/pkg/errors"
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"go.uber.org/atomic"
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"github.com/prometheus/prometheus/pkg/exemplar"
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"github.com/prometheus/prometheus/storage"
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"github.com/prometheus/prometheus/tsdb/record"
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"github.com/prometheus/prometheus/tsdb/tombstones"
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"github.com/prometheus/prometheus/tsdb/wal"
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)
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func (h *Head) loadWAL(r *wal.Reader, multiRef map[uint64]uint64, mmappedChunks map[uint64][]*mmappedChunk) (err error) {
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// Track number of samples that referenced a series we don't know about
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// for error reporting.
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var unknownRefs atomic.Uint64
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var unknownExemplarRefs atomic.Uint64
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// Start workers that each process samples for a partition of the series ID space.
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// They are connected through a ring of channels which ensures that all sample batches
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// read from the WAL are processed in order.
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var (
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wg sync.WaitGroup
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n = runtime.GOMAXPROCS(0)
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inputs = make([]chan []record.RefSample, n)
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outputs = make([]chan []record.RefSample, n)
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exemplarsInput chan record.RefExemplar
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dec record.Decoder
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shards = make([][]record.RefSample, n)
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decoded = make(chan interface{}, 10)
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decodeErr, seriesCreationErr error
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seriesPool = sync.Pool{
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New: func() interface{} {
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return []record.RefSeries{}
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},
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}
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samplesPool = sync.Pool{
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New: func() interface{} {
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return []record.RefSample{}
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},
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}
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tstonesPool = sync.Pool{
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New: func() interface{} {
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return []tombstones.Stone{}
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},
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}
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exemplarsPool = sync.Pool{
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New: func() interface{} {
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return []record.RefExemplar{}
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},
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}
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)
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defer func() {
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// For CorruptionErr ensure to terminate all workers before exiting.
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_, ok := err.(*wal.CorruptionErr)
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if ok || seriesCreationErr != nil {
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for i := 0; i < n; i++ {
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close(inputs[i])
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for range outputs[i] {
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}
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}
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close(exemplarsInput)
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wg.Wait()
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}
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}()
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wg.Add(n)
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for i := 0; i < n; i++ {
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outputs[i] = make(chan []record.RefSample, 300)
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inputs[i] = make(chan []record.RefSample, 300)
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go func(input <-chan []record.RefSample, output chan<- []record.RefSample) {
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unknown := h.processWALSamples(h.minValidTime.Load(), input, output)
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unknownRefs.Add(unknown)
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wg.Done()
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}(inputs[i], outputs[i])
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}
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wg.Add(1)
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exemplarsInput = make(chan record.RefExemplar, 300)
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go func(input <-chan record.RefExemplar) {
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defer wg.Done()
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for e := range input {
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ms := h.series.getByID(e.Ref)
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if ms == nil {
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unknownExemplarRefs.Inc()
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continue
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}
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if e.T < h.minValidTime.Load() {
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continue
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}
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// At the moment the only possible error here is out of order exemplars, which we shouldn't see when
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// replaying the WAL, so lets just log the error if it's not that type.
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err = h.exemplars.AddExemplar(ms.lset, exemplar.Exemplar{Ts: e.T, Value: e.V, Labels: e.Labels})
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if err != nil && err == storage.ErrOutOfOrderExemplar {
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level.Warn(h.logger).Log("msg", "Unexpected error when replaying WAL on exemplar record", "err", err)
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}
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}
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}(exemplarsInput)
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go func() {
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defer close(decoded)
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for r.Next() {
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rec := r.Record()
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switch dec.Type(rec) {
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case record.Series:
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series := seriesPool.Get().([]record.RefSeries)[:0]
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series, err = dec.Series(rec, series)
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if err != nil {
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decodeErr = &wal.CorruptionErr{
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Err: errors.Wrap(err, "decode series"),
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Segment: r.Segment(),
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Offset: r.Offset(),
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}
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return
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}
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decoded <- series
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case record.Samples:
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samples := samplesPool.Get().([]record.RefSample)[:0]
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samples, err = dec.Samples(rec, samples)
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if err != nil {
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decodeErr = &wal.CorruptionErr{
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Err: errors.Wrap(err, "decode samples"),
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Segment: r.Segment(),
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Offset: r.Offset(),
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}
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return
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}
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decoded <- samples
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case record.Tombstones:
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tstones := tstonesPool.Get().([]tombstones.Stone)[:0]
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tstones, err = dec.Tombstones(rec, tstones)
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if err != nil {
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decodeErr = &wal.CorruptionErr{
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Err: errors.Wrap(err, "decode tombstones"),
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Segment: r.Segment(),
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Offset: r.Offset(),
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}
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return
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}
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decoded <- tstones
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case record.Exemplars:
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exemplars := exemplarsPool.Get().([]record.RefExemplar)[:0]
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exemplars, err = dec.Exemplars(rec, exemplars)
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if err != nil {
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decodeErr = &wal.CorruptionErr{
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Err: errors.Wrap(err, "decode exemplars"),
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Segment: r.Segment(),
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Offset: r.Offset(),
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}
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return
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}
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decoded <- exemplars
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default:
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// Noop.
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}
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}
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}()
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// The records are always replayed from the oldest to the newest.
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Outer:
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for d := range decoded {
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switch v := d.(type) {
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case []record.RefSeries:
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for _, walSeries := range v {
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mSeries, created, err := h.getOrCreateWithID(walSeries.Ref, walSeries.Labels.Hash(), walSeries.Labels)
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if err != nil {
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seriesCreationErr = err
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break Outer
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}
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if h.lastSeriesID.Load() < walSeries.Ref {
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h.lastSeriesID.Store(walSeries.Ref)
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}
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mmc := mmappedChunks[walSeries.Ref]
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if created {
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// This is the first WAL series record for this series.
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h.metrics.chunksCreated.Add(float64(len(mmc)))
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h.metrics.chunks.Add(float64(len(mmc)))
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mSeries.mmappedChunks = mmc
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continue
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}
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// There's already a different ref for this series.
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// A duplicate series record is only possible when the old samples were already compacted into a block.
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// Hence we can discard all the samples and m-mapped chunks replayed till now for this series.
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multiRef[walSeries.Ref] = mSeries.ref
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idx := mSeries.ref % uint64(n)
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// It is possible that some old sample is being processed in processWALSamples that
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// could cause race below. So we wait for the goroutine to empty input the buffer and finish
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// processing all old samples after emptying the buffer.
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inputs[idx] <- []record.RefSample{}
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for len(inputs[idx]) != 0 {
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time.Sleep(1 * time.Millisecond)
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}
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// Checking if the new m-mapped chunks overlap with the already existing ones.
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// This should never happen, but we have a check anyway to detect any
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// edge cases that we might have missed.
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if len(mSeries.mmappedChunks) > 0 && len(mmc) > 0 {
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if overlapsClosedInterval(
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mSeries.mmappedChunks[0].minTime,
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mSeries.mmappedChunks[len(mSeries.mmappedChunks)-1].maxTime,
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mmc[0].minTime,
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mmc[len(mmc)-1].maxTime,
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) {
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// The m-map chunks for the new series ref overlaps with old m-map chunks.
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seriesCreationErr = errors.Errorf("overlapping m-mapped chunks for series %s", mSeries.lset.String())
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break Outer
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}
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}
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// Replacing m-mapped chunks with the new ones (could be empty).
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h.metrics.chunksCreated.Add(float64(len(mmc)))
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h.metrics.chunksRemoved.Add(float64(len(mSeries.mmappedChunks)))
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h.metrics.chunks.Add(float64(len(mmc) - len(mSeries.mmappedChunks)))
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mSeries.mmappedChunks = mmc
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// Any samples replayed till now would already be compacted. Resetting the head chunk.
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mSeries.nextAt = 0
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mSeries.headChunk = nil
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mSeries.app = nil
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h.updateMinMaxTime(mSeries.minTime(), mSeries.maxTime())
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}
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//nolint:staticcheck // Ignore SA6002 relax staticcheck verification.
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seriesPool.Put(v)
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case []record.RefSample:
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samples := v
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// We split up the samples into chunks of 5000 samples or less.
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// With O(300 * #cores) in-flight sample batches, large scrapes could otherwise
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// cause thousands of very large in flight buffers occupying large amounts
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// of unused memory.
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for len(samples) > 0 {
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m := 5000
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if len(samples) < m {
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m = len(samples)
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}
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for i := 0; i < n; i++ {
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var buf []record.RefSample
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select {
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case buf = <-outputs[i]:
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default:
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}
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shards[i] = buf[:0]
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}
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for _, sam := range samples[:m] {
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if r, ok := multiRef[sam.Ref]; ok {
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sam.Ref = r
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}
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mod := sam.Ref % uint64(n)
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shards[mod] = append(shards[mod], sam)
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}
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for i := 0; i < n; i++ {
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inputs[i] <- shards[i]
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}
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samples = samples[m:]
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}
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//nolint:staticcheck // Ignore SA6002 relax staticcheck verification.
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samplesPool.Put(v)
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case []tombstones.Stone:
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for _, s := range v {
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for _, itv := range s.Intervals {
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if itv.Maxt < h.minValidTime.Load() {
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continue
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}
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if m := h.series.getByID(s.Ref); m == nil {
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unknownRefs.Inc()
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continue
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}
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h.tombstones.AddInterval(s.Ref, itv)
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}
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}
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//nolint:staticcheck // Ignore SA6002 relax staticcheck verification.
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tstonesPool.Put(v)
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case []record.RefExemplar:
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for _, e := range v {
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exemplarsInput <- e
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}
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//nolint:staticcheck // Ignore SA6002 relax staticcheck verification.
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exemplarsPool.Put(v)
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default:
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panic(fmt.Errorf("unexpected decoded type: %T", d))
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}
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}
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if decodeErr != nil {
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return decodeErr
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}
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if seriesCreationErr != nil {
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// Drain the channel to unblock the goroutine.
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for range decoded {
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}
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return seriesCreationErr
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}
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// Signal termination to each worker and wait for it to close its output channel.
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for i := 0; i < n; i++ {
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close(inputs[i])
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for range outputs[i] {
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}
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}
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close(exemplarsInput)
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wg.Wait()
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if r.Err() != nil {
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return errors.Wrap(r.Err(), "read records")
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}
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if unknownRefs.Load() > 0 || unknownExemplarRefs.Load() > 0 {
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level.Warn(h.logger).Log("msg", "Unknown series references", "samples", unknownRefs.Load(), "exemplars", unknownExemplarRefs.Load())
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}
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return nil
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}
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// processWALSamples adds a partition of samples it receives to the head and passes
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// them on to other workers.
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// Samples before the mint timestamp are discarded.
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func (h *Head) processWALSamples(
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minValidTime int64,
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input <-chan []record.RefSample, output chan<- []record.RefSample,
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) (unknownRefs uint64) {
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defer close(output)
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// Mitigate lock contention in getByID.
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refSeries := map[uint64]*memSeries{}
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mint, maxt := int64(math.MaxInt64), int64(math.MinInt64)
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for samples := range input {
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for _, s := range samples {
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if s.T < minValidTime {
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continue
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}
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ms := refSeries[s.Ref]
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if ms == nil {
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ms = h.series.getByID(s.Ref)
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if ms == nil {
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unknownRefs++
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continue
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}
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refSeries[s.Ref] = ms
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}
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if _, chunkCreated := ms.append(s.T, s.V, 0, h.chunkDiskMapper); chunkCreated {
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h.metrics.chunksCreated.Inc()
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h.metrics.chunks.Inc()
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}
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if s.T > maxt {
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maxt = s.T
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}
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if s.T < mint {
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mint = s.T
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}
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}
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output <- samples
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}
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h.updateMinMaxTime(mint, maxt)
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return unknownRefs
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}
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